Method for booting and dumping a confidential image on a trusted computer system

ABSTRACT

A method for booting and dumping a confidential image on a trusted computer system. Embodiments of the present invention disclose deploying a secure boot image and encrypted client data from a client to a trusted computer system. Embodiments of the present invention disclose booting a confidential image on a trusted computer system. Embodiments of the present invention also disclose a process of dumping a confidential image on the trusted computer system.

TECHNICAL FIELD OF THE INVENTION

The present invention relates generally to security in a cloud computingenvironment, and more particularly to booting and dumping a confidentialimage on a trusted computer system.

BACKGROUND

A trusted computer system has a defined and verifiable function, shroudsthe memory used by the system from inspection, has access to a privatekey that uniquely identifies the system, cannot be inspected fromoutside the system or any software running inside the system, and runssecure firmware that cannot be inspected or modified either from outsidethe trusted computer system or from software running in the trustedcomputer system. On a trusted computer system, the secure firmware hasaccess to the private key of the trusted computer system.

A confidential image can be deployed to the trusted computer system.With the confidential image deployed to the trusted computer system, anyparty who inspects storage outside the trusted system cannot learn thecontents of the confidential image, any party who inspects communicationchannels used for deploying the confidential image to the trustedcomputer system cannot learn the contents of the image.

A standalone dump mechanism can dump an operating system image, anytimeand regardless of the state of the operating system, to a dump medium,provided the system is capable of booting an image. A confidentialstandalone dump image must ensure that the contents of dumped image canonly be observed by the owner of the dumped image.

SUMMARY

In one aspect, a method for booting a confidential image on a trustedcomputer system is provided. The method is implemented by the trustedcomputer system. The method comprises: loading an encrypted client imagekey onto a protected area on the trusted computer system; loading anencrypted boot image onto a secure logical partition on the trustedcomputer system; decrypting, with a private host key, the encryptedclient image key to obtain a client image key in the protected area;decrypting, with the client image key, the encrypted boot image toobtain a boot image and a client data key; and starting the boot image.The boot image mounts encrypted client data which is encrypted with theclient data key.

In another aspect, a method for dumping a confidential image on atrusted computer system is provided. The method is implemented by thetrusted computer system. The method comprises: loading an encryptedclient dumper image key onto a protected area on the trusted computersystem; decrypting, with a private host key stored in the protectedarea, the encrypted client dumper image key to generate a client dumperimage key in the protected area; comparing, the client dumper image keywith a client image key in the protected area; determining whether theclient dumper image key matches the client image key; loading anencrypted dumper including a client dump key onto a secure logicalpartition on the trusted computer system, in response to determiningthat the client dumper image key matches the client image key;decrypting, with the client dumper image key, the encrypted dumper togenerate a dumper including the client dump key; starting the dumper.The dumper generates an encrypted dump by encrypting, with the clientdump key, an image to be dumped in the secure logical partition, thedumper writes the encrypted dump on a client dump device.

In yet another aspect, a method for generating and deploying a secureboot image and encrypted client data to a trusted computer system isprovided. The method is implemented by a client computer. The methodcomprises: generating a client image key; generating a client data key;generating the encrypted client data by encrypting client data, with theclient data key; writing the client data key into a boot image;generating an encrypted boot image by encrypting the boot image, withthe client image key; generating an encrypted client image key, with apublic host key; generating a secure boot image including the encryptedboot image and the encrypted client image key; deploying the secure bootimage and the encrypted client data to the trusted computer system.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a systematic diagram showing deployment of a secure boot imageand encrypted client data from a client to a cloud provider, inaccordance with one embodiment of the present invention.

FIG. 2 is a flowchart showing operational steps for a client to generateand deploy a secure boot image and encrypted client data, in accordancewith one embodiment of the present invention.

FIG. 3 is a systematic diagram showing Initial Program Load (IPL) of asecure boot image by a secure firmware on a trusted computer system, inaccordance with one embodiment of the present invention.

FIG. 4 is a flowchart showing operational steps for Initial Program Load(IPL) of a secure boot image by a secure firmware on a trusted computersystem, in accordance with one embodiment of the present invention.

FIG. 5 is a systematic diagram showing a guest initiated confidentialstandalone dump of a current operating system image, in accordance withone embodiment of the present invention.

FIG. 6 is a flowchart showing operational steps for a confidentialstandalone dump of a current operating system image, in accordance withone embodiment of the present invention.

FIG. 7 is a diagram illustrating components of a client computer device,a cloud provider computer device, or a trusted computer system, inaccordance with one embodiment of the present invention.

DETAILED DESCRIPTION

Embodiments of the present invention disclose a mechanism of deploying asecure boot image and encrypted client data from a client to a trustedcomputer system. Embodiments of the present invention disclose amechanism of booting a confidential image on a trusted computer system.Embodiments of the present invention also disclose a mechanism of aguest initiated confidential standalone dump of an operating systemimage.

FIG. 1 is a systematic diagram showing deployment of secure boot image118 and encrypted client data 119 from client 110 to cloud provider 120,in accordance with one embodiment of the present invention. The systemcomprises client 110 and cloud provider 120. Cloud provider 120comprises trusted computer system 121 and cloud storage 124. Trustedcomputer system 121 is equipped with private host key 123 which is anon-forgeable and non-extractable private key. Public host key 122,which is a public key of an asymmetric key pair and corresponds toprivate host key 123, is managed by provider 120.

Referring to FIG. 1, client 110 receives public host key 122 from cloudprovider 120 and authenticates public host key 122 through certificateauthority 130. Certificate authority 130 may be a vendor of trustedcomputer server 121. Client 110 generates two symmetric keys only knownto client 110: client image key 111 and client data key 114. Client 110uses client data key 114 to encrypt client data 115 and generateencrypted client data 119. Client 110 writes client data key 114 intoraw boot image 113 to generate boot image 116 which comprises raw bootimage 113 and client data key 114. Client 110 uses client image key 111to encrypt boot image 116 and generate encrypted boot image 117. Client110 uses authenticated public host key 122 to encrypt client image key111 and generates encrypted client image key 112. Thus, secure bootimage 118 is generated by client 110, and it includes encrypted clientimage key 112 and encrypted boot image 117 (which includes raw bootimage 113 and client data key 114). Client 110 deploys secure boot image118 and encrypted client data 119 to cloud storage 124.

FIG. 2 is a flowchart showing operational steps for client 110 togenerate and deploy secure boot image 118 and encrypted client data 119,in accordance with one embodiment of the present invention. At step 201,client 110 requests public host key 122 from cloud provider 120. Publichost key 122 is managed by cloud provider 120; it is a public key of anasymmetric key pair and corresponds to private host key 123 kept bytrusted computer system 121. At step 201, client 110 verifies publichost key 122 with certificate authority 130. At step 203, client 110determines whether public host key 122 is a valid key. In response todetermining that public host key 122 is not a valid key, client 110aborts the process of generating and deploying secure boot image 118 andencrypted client data 119.

In response to determining that public host key 122 is a valid key,client 110 at step 204 generates client image key 111 for encrypting aboot image. Client image key 111 is a symmetric key. At step 205, client110 generates client data key 114 for encrypting client data. Clientdata key 114 is also a symmetric key. At step 206, client 110 generatesencrypted client data 119, by encrypting client data 115 with clientdata key 114. At step 207, client 110 writes client data key 114 intoraw boot image 113. At this step, client 110 generates boot image 116which comprises raw boot image 113 and client data key 114. At step 208,client 110 generates encrypted boot image 117 by encrypting boot image116 with client image key 111. At step 209, client 110 generatesencrypted client image key 112 by encrypting client image key 111 withpublic host key 122. At step 210, client 110 generates secure boot image118 including encrypted boot image 117 and encrypted client image key112. At step 211, client 110 deploys secure boot image 118 and encryptedclient data 119 to cloud provider 120.

FIG. 3 is a systematic diagram showing Initial Program Load (IPL) ofsecure boot image 118 by secure firmware 300 on trusted computer system121, in accordance with one embodiment of the present invention. Securefirmware 300 comprises protected area 320 and secure logical partition(LPAR) 310. Protected area 320 is inaccessible by a normal program or anoperating system running in secure LPAR 310, by code running in anotherLPAR, or by an operator or user. Private host key 123 resides inprotected area 320. Shown in (A) of FIG. 3, secure firmware 300 loadsencrypted client image key 112 onto protected area 320 and encryptedboot image 117 onto secure LPAR 310. Shown in (B) of FIG. 3, securefirmware 300 uses private host key 123 to decrypt encrypted client imagekey 112 and thus obtains client image key 111 in protected area 320.Then, secure firmware 300 uses client image key 111 to decrypt encryptedboot image 117 and thus obtains raw boot image 113 and client data key114 in secure LPAR 310. Shown in (C) of FIG. 3, secure firmware 300starts to run raw boot image 113. Shown in (D) of FIG. 3, raw boot image113 mounts encrypted client data 119 and uses client data key 114 todecrypt encrypted client data 119.

FIG. 4 is a flowchart showing operational steps for Initial Program Load(IPL) of secure boot image 118 by secure firmware 300 on trustedcomputer system 120, in accordance with one embodiment of the presentinvention. At step 401, secure firmware 300 loads encrypted client imagekey 112 onto protected area 320. At step 402, secure firmware 300 loadsencrypted boot image 117 into secure LPAR 310. At step 403, usingprivate host key 123 to decrypt encrypted client image key 112, securefirmware 300 obtains client image key 111 in protected area 320. At step404, using client image key 111 to decrypt encrypted boot image 117,secure firmware 300 obtains raw boot image 113 and client data key 114.At step 405, secure firmware 300 starts raw boot image 113. At thisstep, secure firmware 300 transfers the control to the decrypted bootimage—raw boot image 113. At step 406, raw boot image 113 mountsencrypted client data 119 onto secure LPAR 310. At this step, raw bootimage 113 uses client data key 114 to decrypt encrypted client data 119to obtain client data 115. Raw boot image 113 uses client data key 114to decrypt read data and encrypt written data.

FIG. 5 is a systematic diagram showing a guest initiated confidentialstandalone dump of a current operating system image, in accordance withone embodiment of the present invention. Secure dumper image 520comprises encrypted client dumper image key 521 and encrypted dumper522. Encrypted client dumper image key 521 has been generated fromclient dumper image key 511 by client 110, with public host key 122shown in FIG. 1. Encrypted dumper 522 has been generated by client 110,with client dumper image key 511. Encrypted dumper 522 comprises clientdump key 523. Secure firmware 510 comprises protected area 518 andsecure logical partition (LPAR) 515. Protected area 518 is inaccessibleby a normal program or an operating system running in secure LPAR 515,or by an operator or user. When a user on trusted computer system 121initiates a confidential standalone dump process, encrypted clientdumper image key 521 is loaded onto protected area 518 and decryptedwith private host key 123 which resides in protected area 518. Throughdecryption of encrypted client dumper image key 521, client dumper imagekey 511 is generated in protected area 518. Client dumper image key 511is compared to client image key 111 which resides in protected area 518.Client image key 111 has been used to encrypting (as shown in FIGS. 1and 2) raw boot image 113 of the current operating system. If clientdumper image key 511 matches client image key 111, encrypted dumper 522is loaded onto an unused area of secure LPAR 515 and decrypted withclient dumper image key 511; thus, dumper 516 including client dump key523 is generated in secure LPAR 515. The unused area is reserved fordumper 515. Image to be dumped 517 is encrypted with client dump key 523to generate encrypted image to be dumped 525 which is written on clientdump device 524. In another embodiment, client dump key 523 may beincluded in encrypted client dumper image key 521; after encryptedclient dumper image key 521 is decrypted by private host key 123, clientdump key 523 is included in client dumper image key 511.

FIG. 6 is a flowchart showing operational steps for a confidentialstandalone dump of a current operating system image, in accordance withone embodiment of the present invention. At step 601, in response toreceiving a request for a confidential standalone dump process initiatedby a user, secure firmware 510 on trusted computer system 121 loadsencrypted client dumper image key 521 from secure dumper image 520 ontoprotected area 518 of secure firmware 510 on trusted computer system121. Secure dumper image 520 has been generated by a client computersuch as client 110 shown in FIG. 1. Encrypted client dumper image key521 has been generated by the client computer with a public host keysuch as public host key 122 shown in FIG. 1. At step 602, securefirmware 510 on trusted computer system 121 decrypts, using private hostkey 123 stored in protected area 518, encrypted client dumper image key521 to generate client dumper image key 511 in protected area 518.Private host key 123 is a private key of an asymmetric key pair andcorresponds to public host key 122. At step 603, secure firmware 510 ontrusted computer system 121 compares client dumper image key 511 withclient image key 111 stored in protected area 518. Client image key 111has been used to encrypt a boot image (such as raw boot image 113 shownin FIG. 1) of a current operating system. The current operating image isstored in secure LPAR 515. At step 604, secure firmware 510 on trustedcomputer system 121 determines whether client dumper image key 511matches client image key 111.

In response to determining that client dumper image key 511 does notmatch client image key 111, secure firmware 510 on trusted computersystem 121 aborts the confidential standalone dump process. In responseto determining that client dumper image key 511 matches client image key111, secure firmware 510 on trusted computer system 121 at step 605loads encrypted dumper 522 onto a dumper region in secure LPAR 515.Encrypted dumper 522 comprises client dump key 523. Encrypted dumper 522has been generated by a client computer such as client 110 shown in FIG.1, and it has been generated with client dumper image key 511. At step606, secure firmware 510 on trusted computer system 121 decrypts, usingclient dumper image key 511, encrypted dumper 522 so as to generatedumper 516, which includes client dump key 523, in the dumper region insecure LPAR 515. At step 607, secure firmware 510 on trusted computersystem 121 starts dumper 516. At this step, secure firmware 510 ontrusted computer system 121 transfers the control to dumper 516. At step608, dumper 516 generates an encrypted dump (encrypted image to bedumped 525) in secure LPAR 515, by encrypting image to be dumped 517with client dump key 523. At step 609, dumper 516 writes the encrypteddump (encrypted image to be dumped 525) on client dump device 524.

FIG. 7 is a diagram illustrating components of a computer device ofclient 110, a computer device of cloud provider 120, or trusted computersystem 121, in accordance with one embodiment of the present invention.It should be appreciated that FIG. 7 provides only an illustration ofone implementation and does not imply any limitations with regard to theenvironment in which different embodiments may be implemented.

Referring to FIG. 7, computer device 700 includes processor(s) 720,memory 710, and tangible storage device(s) 730. In FIG. 7,communications among the above-mentioned components of computer device700 are denoted by numeral 790. Memory 710 includes ROM(s) (Read OnlyMemory) 711, RAM(s) (Random Access Memory) 713, and cache(s) 715. One ormore operating systems 731 and one or more computer programs 733 resideon one or more computer readable tangible storage device(s) 730.Computer device 700 further includes I/O interface(s) 750. I/Ointerface(s) 750 allows for input and output of data with externaldevice(s) 760 that may be connected to computer device 700. Computerdevice 700 further includes network interface(s) 740 for communicationsbetween computer device 700 and a computer network.

The present invention may be a system, a method, and/or a computerprogram product. The computer program product may include a computerreadable storage medium (or media) having computer readable programinstructions thereon for causing a processor to carry out aspects of thepresent invention.

The computer readable storage medium can be a tangible device that canretain and store instructions for use by an instruction executiondevice. The computer readable storage medium may be, for example, but isnot limited to, an electronic storage device, a magnetic storage device,an optical storage device, an electromagnetic storage device, asemiconductor storage device, or any suitable combination of theforegoing. A non-exhaustive list of more specific examples of thecomputer readable storage medium includes the following: a portablecomputer diskette, a hard disk, a random access memory (RAM), aread-only memory (ROM), an erasable programmable read-only memory (EPROMor Flash memory), a static random access memory (SRAM), a portablecompact disc read-only memory (CD-ROM), a digital versatile disk (DVD),a memory stick, a floppy disk, a mechanically encoded device, such aspunch-cards or raised structures in a groove having instructionsrecorded thereon, and any suitable combination of the foregoing. Acomputer readable storage medium, as used herein, is not to be construedas being transitory signals per se, such as radio waves or other freelypropagating electromagnetic waves, electromagnetic waves propagatingthrough a waveguide or other transmission media (e.g., light pulsespassing through a fiber-optic cable), or electrical signals transmittedthrough a wire.

Computer readable program instructions described herein can bedownloaded to respective computing/processing devices from a computerreadable storage medium or to an external computer or external storagedevice via a network, for example, the Internet, a local area network(LAN), a wide area network (WAN), and/or a wireless network. The networkmay comprise copper transmission cables, optical transmission fibers,wireless transmission, routers, firewalls, switches, gateway computersand/or edge servers. A network adapter card or network interface in eachcomputing/processing device receives computer readable programinstructions from the network and forwards the computer readable programinstructions for storage in a computer readable storage medium withinthe respective computing/processing device.

Computer readable program instructions for carrying out operations ofthe present invention may be assembler instructions,instruction-set-architecture (ISA) instructions, machine instructions,machine dependent instructions, microcode, firmware instructions,state-setting data, or either source code or object code written in anycombination of one or more programming languages, including an objectoriented programming language such as Smalltalk, C++, and conventionalprocedural programming languages, such as the “C” programming language,or similar programming languages. The computer readable programinstructions may execute entirely on the user's computer, partly on theuser's computer, as a stand-alone software package, partly on the user'scomputer and partly on a remote computer, or entirely on the remotecomputer or server. In the latter scenario, the remote computer may beconnected to the user's computer through any type of network, includinga local area network (LAN) or a wide area network (WAN), or theconnection may be made to an external computer (for example, through theInternet using an Internet Service Provider). In some embodiments,electronic circuitry including, for example, programmable logiccircuitry, field-programmable gate arrays (FPGA), or programmable logicarrays (PLA) may execute the computer readable program instructions byutilizing state information of the computer readable programinstructions to personalize the electronic circuitry in order to performaspects of the present invention.

Aspects of the present invention are described herein with reference toflowchart illustrations and/or block diagrams of methods, apparatus(systems), and computer program products according to embodiments of theinvention. It will be understood that each block of the flowchartillustrations and/or block diagrams, and combinations of blocks in theflowchart illustrations and/or block diagrams, can be implemented bycomputer readable program instructions.

These computer readable program instructions may be provided to aprocessor of a general purpose computer, special purpose computer, orother programmable data processing apparatus to produce a machine, suchthat the instructions, which execute via the processor of the computeror other programmable data processing apparatus, create means forimplementing the functions/acts specified in the flowchart and/or blockdiagram block or blocks. These computer readable program instructionsmay also be stored in a computer readable storage medium that can directa computer, a programmable data processing apparatus, and/or otherdevices to function in a particular manner, such that the computerreadable storage medium having instructions stored therein comprises anarticle of manufacture, including instructions which implement aspectsof the function/act specified in the flowchart and/or block diagramblock or blocks.

The computer readable program instructions may also be loaded onto acomputer, other programmable data processing apparatus, or other deviceto cause a series of operational steps to be performed on the computer,other programmable apparatus, or other device to produce a computerimplemented process, such that the instructions which execute on thecomputer, other programmable apparatus, or other device implement thefunctions/acts specified in the flowchart and/or block diagram block orblocks.

The flowchart and block diagrams in the FIGs illustrate thearchitecture, functionality, and operation of possible implementationsof systems, methods, and computer program products according to variousembodiments of the present invention. In this regard, each block in theflowchart or block diagrams may represent a module, segment, or portionof instructions, which comprises one or more executable instructions forimplementing the specified logical function(s). In some alternativeimplementations, the functions noted in the block may occur out of theorder noted in the FIGs. For example, two blocks shown in successionmay, in fact, be executed substantially concurrently, or the blocks maysometimes be executed in the reverse order, depending upon thefunctionality involved. It will also be noted that each block of theblock diagrams and/or flowchart illustration, and combinations of blocksin the block diagrams and/or flowchart illustration, can be implementedby special purpose hardware-based systems that perform the specifiedfunctions or acts or carry out combinations of special purpose hardwareand computer instructions.

What is claimed is:
 1. A method for booting a confidential image on atrusted computer system, the method comprising: loading, by the trustedcomputer system, an encrypted client image key onto a protected area onthe trusted computer system; loading, by the trusted computer system, anencrypted boot image onto a secure logical partition on the trustedcomputer system; decrypting, by the trusted computer system, theencrypted client image key to obtain a client image key in the protectedarea, with a private host key; decrypting, by the trusted computersystem, the encrypted boot image to obtain a boot image and a clientdata key, with the client image key; and starting, by the trustedcomputer system, the boot image; wherein the boot image mounts encryptedclient data which is encrypted with the client data key.
 2. The methodof claim 1, further comprising: generating, by a client computer, theclient image key; generating, by the client computer, the client datakey; generating, by the client computer, the encrypted client data byencrypting the client data, with the client data key; writing, by theclient computer, the client data key into the boot image; generating, bythe client computer, the encrypted boot image by encrypting the bootimage, with the client image key; generating, by the client computer,the encrypted client image key, with a public host key; generating, bythe client computer, a secure boot image including the encrypted bootimage and the encrypted client image key; and deploying, by the clientcomputer, the secure boot image and the encrypted client data to thetrusted computer system.
 3. The method of claim 2, wherein the publichost key is a public key of an asymmetric key pair and corresponds tothe private host key.
 4. The method of claim 1, wherein the protectedarea is in secure firmware of the trusted computer system, inaccessibleby a normal program and an operating system running inside or outsidethe secure logical partition of the trusted computer system, andinaccessible by a user.
 5. The method of claim 1, wherein the privatehost key is in the protected area on the trusted computer system.
 6. Themethod of claim 1, wherein the client data key is used by the boot imageto decrypt read data from a mounted encrypted client data volume andencrypt data written to the mounted encrypted client data volume.
 7. Amethod for dumping a confidential image on a trusted computer system,the method comprising: loading, by the trusted computer system, anencrypted client dumper image key onto a protected area on the trustedcomputer system; decrypting, by the trusted computer system, theencrypted client dumper image key to generate a client dumper image keyin the protected area, with a private host key stored in the protectedarea; comparing, by the trusted computer system, the client dumper imagekey with a client image key in the protected area; determining, by thetrusted computer system, whether the client dumper image key matches theclient image key; loading, by the trusted computer system, an encrypteddumper including a client dump key onto a secure logical partition onthe trusted computer system, in response to determining that the clientdumper image key matches the client image key; decrypting, by thetrusted computer system, with the client dumper image key, the encrypteddumper to generate a dumper including the client dump key; starting, bythe trusted computer system, the dumper; and wherein the dumpergenerates an encrypted dump by encrypting, with the client dump key, animage to be dumped in the secure logical partition, the dumper writesthe encrypted dump on a client dump device.
 8. The method of claim 7,wherein the protected area is in secure firmware of the trusted computersystem, inaccessible by a normal program and an operating system runningin the secure logical partition of the trusted computer system, andinaccessible by a user.
 9. The method of claim 7, wherein the clientimage key in the protected area is used to encrypt a boot image of acurrent operating system stored in the secure logical partition on thetrusted computer system.
 10. The method of claim 7, wherein theencrypted client dumper image key is generated, with a public host key,by a client computer, the public host key is a public key of anasymmetric key pair and corresponds to the private host key.
 11. Themethod of claim 7, wherein the encrypted dumper is generated, with theclient dumper image key, by a client computer.
 12. The method of claim7, wherein the client dump key is included in the dumper or the clientdumper image key.
 13. The method of claim 7, wherein the dumper isstored in an area of the secure logical partition which is reserved forthe dumper.
 14. A method for generating and deploying a secure bootimage and encrypted client data to a trusted computer system, the methodcomprising: generating, by a client computer, a client image key;generating, by the client computer, a client data key; generating, bythe client computer, the encrypted client data by encrypting clientdata, with the client data key; writing, by the client computer, theclient data key into a boot image; generating, by the client computer,an encrypted boot image by encrypting the boot image, with the clientimage key; generating, by the client computer, an encrypted client imagekey, with a public host key; generating, by the client computer, asecure boot image including the encrypted boot image and the encryptedclient image key; and deploying, by the client computer, the secure bootimage and the encrypted client data to the trusted computer system. 15.The method of claim 14, further comprising: loading, by the trustedcomputer system, the encrypted client image key onto a protected area onthe trusted computer system; loading, by the trusted computer system,the encrypted boot image onto a secure logical partition on the trustedcomputer system; decrypting, by the trusted computer system, theencrypted client image key to obtain the client image key in theprotected area, with a private host key; decrypting, by the trustedcomputer system, the encrypted boot image to obtain the boot image andthe client data key, with the client image key; and starting, by thetrusted computer system, the boot image; wherein the boot image mountsencrypted client data which is encrypted with the client data key. 16.The method of claim 15, wherein the private host key is in the protectedarea on the trusted computer system.
 17. The method of claim 15, whereinthe protected area is in secure firmware of the trusted computer system,inaccessible by a normal program and an operating system running insideor outside the secure logical partition of the trusted computer system,and inaccessible by a user.
 18. The method of claim 15, wherein theclient data key is used by the boot image to decrypt read data from amounted encrypted client data volume and encrypt data written to themounted encrypted client data volume.
 19. The method of claim 14,wherein the public host key is a public key of an asymmetric key pairand corresponds to a private host key.